<!DOCTYPE html>  
<html lang="zh-CN">  
<head>  
    <meta charset="UTF-8">  
    <meta name="viewport" content="width=device-width, initial-scale=1.0">  
    <title>登录表单</title>  
    <style>  
        body {  
            font-family: Arial, sans-serif;  
            background-color: #f4f4f4;  
            display: flex;  
            justify-content: center;  
            align-items: center;  
            height: 100vh;  
            margin: 0;  
        }  
  
        form {  
            background-color: #ffffff;  
            padding: 20px;  
            border-radius: 8px;  
            box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);  
        }  
  
        input[type="text"],  
        input[type="password"] {  
            width: calc(100% - 22px);  
            padding: 10px;  
            margin: 8px 0;  
            display: inline-block;  
            border: 1px solid #ccc;  
            border-radius: 4px;  
            box-sizing: border-box;  
        }  
  
        input[type="submit"] {  
            width: 100%;  
            background-color: #4CAF50;  
            color: white;  
            padding: 14px 20px;  
            margin: 8px 0;  
            border: none;  
            border-radius: 4px;  
            cursor: pointer;  
        }  
  
        input[type="submit"]:hover {  
            background-color: #45a049;  
        }  
    </style>  
</head>  
<body>  
    <form action="/login" method="post">  
        <input type="text" name="username" placeholder="用户名"><br/>  
        <input type="password" name="password" placeholder="密码"><br/>  
        <input type="submit" value="提交" name="submit">  
    </form>  
</body>  
</html>